FIG. 2 shows a sectional view of a conventional general bipolar transistor. On a silicon substrate 20 are silicon oxide films 21, 22, 30 and 31, a highly-doped n-type collector area 23, a low-doped n-type collector area 24, a p-type base area 25, an n-type emitter area 26, a highly-doped p-type link base area 27, a polycrystal silicon base electrode 28, a polycrystal emitter area 29, and metallic electrodes 32 and 33.
This conventional transistor is shown, for example, in "IEEE, Trans. Electron Dev., ED-34, No. 11 (1987) pp. 2246-2245".